Swimming pool backwashing device



FIG. 1 is a front elevational view of a swimming pool backwashing device showing my new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a close up view of the left side hose connection; and,

FIG. 8 is a close up view of the right side hose connection.

The broken line showing a hose is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a swimming pool backwashing device, as shown and described. 